Macrolide compounds, their preparation and their use

ABSTRACT

Compounds with acaricidal, insecticidal and anthelmintic activities have the formula: ##STR1## wherein: --X--Y-- is selected from the group consisting of --CH 2  --CH 2  --, --CH 2  --CHOH--, --CH═CH--, and --CH 2  --C(═O)--; 
     R 1  is selected from the group consisting of a methyl group, an ethyl group, an isopropyl group, a sec-butyl group and groups of formula --C(CH 3 )═CHR 5  in which R 5  is selected from the group consisting of a methyl group, an ethyl group and an isopropyl group; 
     R 2  represents a group of formula --(CH 2 ) n  --C(R 6 )═C(R 7 )(R 8 ) in which n is 0, 1 or 2, R 6  and R 7  each is selected from the group consisting of a hydrogen atom and a methyl group and R 8  is selected from the group consisting of a hydrogen atom, a C 1-4  alkyl group, a phenyl group and a phenyl group substituted with at least one substituent selected from the group consisting of halogen, methyl and nitro substitutents; 
     R 3  is selected from the group consisting of a hydrogen atom, a methyl group, a hydroxy-protecting group, an ester-forming carboxylic acid residue, and an ester-forming carbonic acid residue; and 
     R 4  is selected from the group consisting of a hydrogen atom and an α-L-oleandrosyl-α-L-oleandrosyloxy group, with the proviso that R 4  represents a hydrogen atom when the group R 1  is selected from the group consisting of a methyl group, an ethyl group, and groups of formula --C(CH 3 )═CHR 5  in which R 5  is selected from the group consisting of a methyl group, an ethyl group and an isopropyl group.

BACKGROUND OF THE INVENTION

The present invention is concerned with a series of new macrolidecompounds. The new compounds have valuable acaricidal, insecticidal andanthelmintic activities which are generally referred to herein asparasiticidal activities. This invention also provides methods ofpreparing the novel macrolide compounds and parasiticidal compositionscontaining the compounds, and methods for using them.

The new compounds provided by this invention are macrolides chemicallyrelated to the known milbemycins, avermectins, and similar compounds.There are several classes of known compounds with a structure based on a16-membered macrolide ring. They are obtained by fermentation of variousmicroorganisms or semi-synthetically by chemical derivatization of suchnatural fermentation products, and exhibit acaricidal, insecticidal,anthelmintic and other antiparasitic activities. The milbemycins andavermectins are examples of two such classes of known compounds, butvarious other classes also exist and are identified by different namesor code numbers. The names for these various macrolide compounds havegenerally been taken from the names or code numbers of themicro-organisms which produce the naturally occurring members of eachclass, and these names have then been extended to cover the chemicalderivatives of the same class, with the result that there has been nostandardized systematic nomenclature for general use with suchcompounds.

In order to avoid confusion, reference in this patent specification willbe made to names based on the hypothetical parent compound representedby formula (A): ##STR2## For the avoidance of doubt, formula (A) alsoshows the numbering of some carbon atoms most relevant to the compoundsof the present invention. The methyl group at the 4-position has beennumbered C-26.

The naturally produced milbemycins form a series of compounds.Milbemycins A₃ and A₄, among others, were disclosed in U.S. Pat. No.3,950,360, and milbemycin D was disclosed in U.S. Pat. No. 4,346,171,where it was referred to as "Compound B-41D". These compounds may berepresented by the above formula (A) in which position 25 is substitutedrespectively with a methyl group, an ethyl group or an isopropyl group.The milbemycin analogue substituted at position 25 with a sec-butyl wasdisclosed in U.S. Pat. No. 4,173,571.

Various derivatives of the original milbemycins have been prepared andtheir activities have been investigated. For example, 5-esterifiedmilbemycins have been disclosed in U.S. Pat. Nos. 4,201,861, 4,206,205,4,173,571, 4,171,314, 4,203,976, 4,289,760, 4,457,920, 4,579,864 and4,547,491; in European Patent Specifications 8184, 102,721, 115,930,142,969, 180,539 and 184,989; and in Japanese Patent Applications Kokai57-120589 and 59-16894.

13-Hydroxy-5-ketomilbemycin derivatives have been disclosed in U.S. Pat.No. 4,423,209. Milbemycin 5-oxime derivatives were disclosed in U.S.Pat. No. 4,547,520 and European Patent Specification 203,832. BritishPatent Specification 2,168,345 disclosed milbemycin derivatives having acarboxy or esterified carboxy substituent at position 13 in combinationwith a hydroxy or esterified hydroxy substituent at position 5.

Like the milbemycins, the avermectins are based upon the same16-membered macrolide ring compound. The avermectins were disclosed, forexample in J Antimicrob Agents Chemother, 1979, 15, 361 (1979) and J AmChem Soc, 1981, 103. 4216. These compounds may be represented by theabove formula (A) but with position 13 substituted with a4'-(α-L-oleandrosyl)-α-L-oleandrosyloxy group. Position 25 may besubstituted with an isopropyl group or a sec-butyl group, and eitherthere is a carbon-carbon double bond between positions 22 and 23, orthere is a hydroxy group at position 23.

The avermectins are defined as follows:

    ______________________________________    avermectin              C.sub.22 -C.sub.23                          R.sub.25 R.sub.23                                          R.sub.5    ______________________________________    A.sub.1 a db          sec-Bu   H      OMe    A.sub.l b db          i-Pr     H      OMe    A.sub.2 a sb          sec-Bu   OH     OMe    A.sub.2 b sb          i-Pr     OH     OMe    B.sub.1 a db          sec-Bu   H      OH    B.sub.1 b db          i-Pr     H      OH    B.sub.2 a sb          sec-Bu   OH     OH    B.sub.2 b sb          i-Pr     OH     OH    ______________________________________

In the above table, R₂₅ is a substituent at the 25 position; R₂₃ is asubstituent at the 23 position; and R₅ is a substituent at the 5position; "db" indicates a double bond between positions 22 and 23; and"sb" indicates a single bond between positions 22 and 23.

The 23-keto derivatives of avermectin A₂ a, A₂ b, B₂ a and B₂ b areknown from U.S. Pat. No. 4,289,760. 22,23-Dihydroavermectins may beobtained by reduction of the double bond between the 22 and 23 positionsand were disclosed in U.S. Pat. No. 4,199,569. The aglyclone derivativesof the avermectins, which are milbemycin analogues, have sometimes beenreferred to in the literature as C-076 compounds, and variousderivatives are known. For example, U.S. Pat. No. 4,201,861 disclosedsuch derivatives substituted with a lower alkanoyl group at position 13.

European Patent Specification 74,758 disclosed avermectin compoundswhich are derivatized at the 4-methyl group. The conversion of the4-methyl group to a hydroxymethyl group is described, along with theformation of various oxymethyl derivatives such as acetyloxymethyl,benzoyloxymethyl and other carbonyloxymethyl compounds.

European Patent Specification 170,006 disclosed a family of bioactivecompounds produced by fermentation, identified collectively by the codenumber LL-F28249. Some of these have a 16-membered macrolide structurecorresponding to the above formula (A), substituted with hydroxy atposition 23 and with a 1-methyl-1-propenyl, 1-methyl-1-butenyl or1,3-dimethyl-1-butenyl at position 25. In these compounds, the hydroxyat position 5 may also be replaced by methoxy.

The same or similar compounds identified as S-541 compounds are knownfrom British Patent Specification 2,166,436. The 23-keto derivatives and23-deoxy derivatives of S-541 are known from Belgian Patent 904,709.S-541 deravitives with a carbon-carbon double bond at positions 22 and23 were disclosed in European Patent Specification 215,654. The26-hydroxy and 26-C₁₋₄ alkanoyloxy derivatives of S-541 and of the23-keto and 23-deoxy derivatives of S-541 are known from European PatentSpecification 237,341.

British Patent Specification 2,176,182 disclosed another group ofmacrolide antibiotics corresponding to the above formula (A), with ahydroxy or substituted hydroxy group at position 5, a hydroxy,substituted hydroxy or keto group at position 23, and an α-branchedalkenyl group at position 25.

A yet further group of related macrolide derivatives was disclosed inJapanese Patent Application Kokai 62-29590. These have a structurecorresponding to the above formula (A), with a hydroxy or methoxy groupat position 5. Position 13 of the ring can be substituted with a4'-(α-L-oleandrosyl)-α-L-oleandrosyloxy group, as in the avermectins,and there may be a carbon-carbon double bond between positions 22 and23, or alternatively position 23 may be substituted with a hydroxygroup. The substituent at position 25 is of a type not found in thenaturally produced milbemycins and avermectins, and includes variousα-branched alkyl, alkenyl, alkynyl, alkoxyalkyl, alkylthioalkyl andcycloalkylalkyl groups, or cycloalkyl, cycloalkenyl or heterocyclicgroups. This 25-substituent is introduced by adding the correspondingcarboxylic acid or derivative thereof to the fermentation broth of anavermectin-producing micro-organism.

The various classes of milbemycin-related macrolide compounds describedabove are all said to have one or more types of activity as antibiotic,anthelmintic, ectoparasiticidal, acaricidal or other pesticidal agents.However, there is still a continuing need to provide compounds withmodified activity against one or more classes of parasites.

OBJECTS OF THIS INVENTION

Accordingly, it is an object of the present invention to providemacrolide compounds having modified parasiticidal activity. It isanother object of the invention to provide methods for preparing suchcompounds. It is a still further object of the invention to provideparasiticidal compositions and methods based on the compounds.

SUMMARY OF THE INVENTION

It has now been discovered that the activity of milbemycin derivativescan be modified by introducing an unsaturated ester group at the4-position in place of the 4-methyl group. Specifically, the presentinvention provides 26-alkenoyloxy derivatives of the milbemycins andrelated macrolides.

Thus, the invention provides compounds having the formula ##STR3##wherein: --X--Y-- represents --CH₂ --CH₂ --, --CH₂ --CHOH--, --CH═CH--,or --CH₂ --C(═O)--;

R¹ represents a methyl group, an ethyl group, an isopropyl group, asec-butyl group or a group of formula --C(CH₃)═CHR⁵ in which R⁵represents a methyl group, an ethyl group or an isopropyl group;

R² represents a group of formula --(CH₂)_(n) --C(R⁶)═C(R⁷)(R⁸) in whichis 0, 1 or 2, R⁶ and R⁷ each represents a hydrogen atom or a methylgroup and R⁸ represents a hydrogen atom, a C₁₋₄ alkyl group, a phenylgroup or a phenyl group substituted with one or more halogen, methyl ornitro groups;

R³ represents a hydrogen atom, a methyl group, a hydroxy-protectinggroup or an ester-forming carboxylic or carbonic acid residue; and

R⁴ represents a hydrogen atom or an α-L-oleandrosyl-α-L-oleandrosyloxygroup, with the proviso that R⁴ represents a hydrogen atom when thegroup R¹ represents a methyl group, an ethyl group, or a group offormula --C(CH₃)═CHR⁵ in which R⁵ represents a methyl group, an ethylgroup or an isopropyl group.

The invention still further provides a parasiticidal composition whichmay have an anthelmintic, acaricidal, insecticidal, or other activity.The composition comprises a compound of formula (I) in admixture with apharmaceutically, agriculturally, veterinarily or horticulturallyacceptable carrier or diluent.

The invention still further provides a method of treating or protectinganimals (which may be human or non-human) or plants from damage byparasites selected from acarids, helminths and insects, which methodcomprises applying or administering a compound of formula (I) to saidanimals, to said plants or to seeds of said plants or to a locusincluding said animals, plants or seeds.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In the compounds of formula (I), where R² represents a group of theformula --C(CH₃)═CHR⁵, the group R² is a 1-methyl-1-propenyl,1-methyl-1-butenyl or 1,3-dimethyl-1-butenyl group.

Where R³ is a hydroxy-protecting group, it may be any of thoseconventionally employed for this purpose. For example, the protectinggroup may be a silyl group represented by the formula Si(R')(R")(R'") inwhich R', R" and R'" each represents a C₁₋₄ alkyl group, a benzyl groupor a phenyl group. Examples of the silyl group include trimethylsilyl,triethylsilyl, tripropylsilyl, triisopropylsilyl,diisopropylmethylsilyl, t-butyldimethylsilyl, dimethylphenylsilyl,t-butyldiphenylsilyl, triphenylsilyl and tribenzylsilyl groups. Amongstthese groups, trimethylsilyl, triethylsilyl and t-butyldimethylsilylgroups are preferred. The protecting group can also be a residue of acarboxylic or carbonic acid residue, as separately mentioned.

When R³ is an acid residue, there is no particular limitation on thenature of the acid, and it can be selected from a wide variety ofcarboxylic acids and carbonic acids, since it appears that thebiological activity of compounds of formula (I) is attributable to theformation of compounds in which --OR³ is a hydroxy group. As mentionedabove, the literature contains many examples of suitable acids forforming 5-esterified milbemycins, and such acids can readily be adoptedfor the compounds of the present invention.

Without being exhaustive, R³ when a residue of an ester-formingcarboxylic or carbonic acid can be of the formula --CO--(O)_(n) --R¹¹,wherein is 0 or 1; and R¹¹ represents a straight or branched chain C₁₋₁₈alkyl group, a C₃₋₇ cycloalkyl group, a C₇₋₉ aralkyl group, a C₂₋₆alkenyl or alkynyl group, a C₆₋₁₀ aryl group or a monocyclic or fusedheterocyclic group having from 5 to 10 ring atoms and containing atleast one oxygen, sulfur or nitrogen atom. The group R¹¹ may optionallyhave one or more substituents, such as for example an alkyl, alkoxy,alkoxyalkyl, halogen, haloalkyl, alkoxycarbonyl, acyloxy, hydroxy,carboxy, amino, mono- to trialkyl-amino, acylamino, cyano, carbamoyl,mono- or di-alkylcarbamoyl, mercapto, alkylthio, alkylsulfinyl,alkylsulfonyl, nitro, phenoxy, halophenoxy, alkylsulfonyloxy,arylsulfonyloxy, cyanothio group, and 5- or 6-membered heterocyclicgroups containing at least one oxygen, sulfur or nitrogen atom. Wherethe substituent contains a carbon atom or atoms, the number of thecarbon atoms is suitably from 1 to 9. Where R¹¹ itself is an alkyl,alkenyl or alkynyl group, the substituent is not an alkyl, alkoxyalkylor haloalkyl group.

Particular examples of acid residues suitable for use ashydroxy-protecting groups include a lower aliphatic acyl group such as aformyl, acetyl, chloroacetyl, dichloroacetyl, trichloroacetyl,trifluoroacetyl, methoxyacetyl, propionyl, n-butyryl,(E)-2-methyl-2-butenoyl, isobutyryl, pentanoyl or pivaloyl group; or anaromatic acyl group such as a benzoyl, o-(dibromoethyl)benzoyl,o-(methoxycarbonyl)benzoyl, p-phenylbenzoyl, 2,4,6-trimethylbenzoyl,p-toluoyl, p-anisoyl, p-chlorobenzoyl, p-nitrobenzoyl, o-nitrobenzoyl orα-naphthoyl qroup.

Preferred compounds of formula (I) include those wherein:

(a) --X--Y-- is --CH₂ --CH₂ --, --CH₂ --CHOH--, or --CH₂ --C(═O)--;

(b).(i) R¹ is a methyl group, an ethyl group or an isopropyl group andR⁴ is a hydrogen atom; or

(b).(ii) R¹ is an isopropyl group or a sec-butyl group and R⁴ is anα-L-oleandrosyl-α-L-oleandrosyloxy group; or

(b).(iii) R¹ is a group of formula --C(CH₃)═CHR⁵ (in which R⁵ is asdefined above) and R⁴ is a hydrogen atom;

(c) R² is a group of formula --CH═C(CH₃)(R¹⁰), wherein R¹⁰ is a methylgroup or an ethyl group.

(d) R³ is a hydrogen atom, a lower alkanoyl group having from 1 to 4carbon atoms (such as an acetyl or propionyl group). or a loweralkoxycarbonyl group having from 2 to 5 carbon atoms (such as anethoxycarbonyl group).

Particularly preferred compounds are those in which --X--Y-- is --CH₂--CH₂ --, R¹ is a methyl group or an ethyl group, R² is a2-methyl-1-propenyl group, and R³ and R⁴ are hydrogen atoms.

Specific examples of preferred compounds of this invention include thosegiven in the following table where the structure is given in terms ofthe formula (I) which is repeated here for convenience:

    __________________________________________________________________________     ##STR4##    No.       XY      R.sub.1                   R.sub.2      R.sup.3                                      R.sup.4    __________________________________________________________________________     1 CH.sub.2CH.sub.3               Me  CHC(CH.sub.3).sub.2                                H     H     2 CH.sub.2CH.sub.2               Me  CHC(CH.sub.3)(C.sub.2 H.sub.5)                                H     H     3 CH.sub.2CH.sub.2               Et  CHC(CH.sub.3).sub.2                                H     H     4 CH.sub.2CH.sub.2               Et  CHC(CH.sub.3)(C.sub.2 H.sub.5)                                H     H     5 CH.sub.2CH.sub.2               Et  CHCHCH.sub.3 H     H      6       CH.sub.2CH.sub.2               Et  C(CH.sub.3)CHCH.sub.3                                H     H     7 CH.sub.2CH.sub.2               Et  CHCH(CH.sub.2).sub.2 CH.sub.3                                H     H     8 CH.sub.2CH.sub.2               Et  CHCHC(CH.sub.3).sub.2                                H     H     9 CH.sub.2CH.sub.2               Et  CH.sub.2 CHCHC.sub.2 H.sub.5                                H     H    10 CH.sub.2CH.sub.2               Et  CH.sub.2 CH.sub.2 CHCH.sub.2                                H     H    11 CH.sub.2CH.sub.2               Et  CHCH-phenyl  H     H    12 CH.sub.2CH.sub.2               Et  CHCH-p-chlorophenyl                                H     H    13 CH.sub.2CH.sub.2               Et  CHC(CH.sub.3).sub.2                                BMS   H    14 CH.sub.2CH.sub.2               Et  CHC(CH.sub.3).sub.2                                COC.sub.2 H.sub.5                                      H    15 CH.sub.2CH.sub.2               Et  CHC(CH.sub.3).sub.2                                COOC.sub.2 H.sub.5                                      H    16 CH.sub.2CH.sub.2               i-Pr                   CHC(CH.sub.3).sub.2                                H     H    17 CH.sub.2CH.sub.2               sec-Bu                   CHC(CH.sub.3).sub.2                                H     α    18 CHCH    sec-Bu                   CHC(CH.sub.3).sub.2                                H     α    19 CH.sub.2CH.sub.2               DMB CHC(CH.sub.3).sub.2                                H     H    20 CH.sub.2CHOH               DMB CHC(CH.sub.3).sub. 2                                H     H    21 CH.sub.2C(O)               DMB CHC(CH.sub.3).sub.2                                H     H    __________________________________________________________________________     In this table;     BMS: tbutyldimethylsilyl     α: α-Loleandrosyl-α-L-oleandrosyloxy     DMB: 1,3dimethyl-1-butenyl

The compounds of the above table are named as follows:

1. 26-(3-Methyl-2-butenoyloxy)milbemycin A₃

2. 26-(3-Methyl-2-pentenoyloxy)milbemycin A₃

3. 26-(3-Methyl-2-butenoyloxy)milbemycin A₄

4. 26-(3-Methyl-2-pentenoyloxy)milbemycin A₄

26-(2-Butenoyloxy)milbemycin A₄

26-(2-Methyl-2-butenoyloxy)milbemycin A₄

26-(2-Hexenoyloxy)milbemycin A₄

26-(4-Methyl-2-pentenoyloxy)milbemycin A₄

9. 26-(3-Hexenoyloxy)milbemycin A₄

10. 26-(4-Pentenoyloxy)milbemycin A₄

11. 26-Cinnamoyloxymilbemycin A₄

12. 26-p-Chlorocinnamoyloxymilbemycin A₄

13. 5-O-t-Butyldimethylsilyl-2-(3-methyl-2-butenyloxy)milbemycin A₄

14. 5-O-propionyl-2-(3-methyl-2-butenoyloxy)milbemycin A₄

15. 5-O-Ethoxycarbonyl-2-(3-methyl-2-butenoyloxy)milbemycin A₄

16. 26-(3-Methyl-2-butenoyloxy)milbemycin D

17. 26-(3-Methyl-2-butenoyloxy)ivermectin B_(1a)

18. 26-(3-Methyl-2-butenoyloxy)avermectin B_(1a)

19. 23-Deoxy-26-(3-methyl-2-butenoyloxy) S-541A

20. 26-(3-Methyl-2-butenoyloxy) S-541A

21. 23-Keto-26-(3-methyl-2-butenoyloxy) S-541A.

Of these compounds, there is a particular preference for Compounds 1, 2,3, 4, 7, 8, 10, 11, 14, 15, 16, 17, 18, 19, 20 and 21: and especiallyfor Compounds 1, 2, 3, 4, 16, 17, 18, 19, 20 and 21.

The compounds of formula (I) of this invention can be prepared by thesteps shown in the following reaction scheme (where the groups --X--Y--,and R¹ to R⁴ are as defined above): ##STR5##

In the reaction scheme, the step A comprises a selective oxidation ofthe 4-methyl group, that is to say the methyl group attached to the4-position of the milbemycin molecule, to yield a 4-hydroxymethyl group.This reaction is known as the "Sharpless reaction" or the "Sharplessoxidation", and is an allyl oxidation using selenium dioxide andt-butylhydroperoxide.

It is already known to apply the Sharpless reaction to macrolides of thetype of formula (II), and the reader is now spefically referred toEuropean Patent 74758 and European Patent Specification 237,341, bothincorporated herein by reference. Therefore, the present Step A may beperformed under conditions similar to those disclosed in these patentspecifications.

Thus, the step A involves oxidizing the 4-methyl compound of the formula(II) with t-butyl hydroperoxide in the presence of a catalytic amount ofselenium dioxide which oxidizes the 4-methyl group to a 4-hydroxymethylgroup and is itself oxidized in the process. The t-butyl hydroperoxideoxidizes the reduced selenium compounds back to selenium dioxide forfurther oxidation of the molecule. In this way only a small, catalyticamount of the selenium dioxide is required.

The reaction is carried out in an inert solvent which is not susceptibleto oxidation. Methylene chloride is preferred, though ethyl acetate,tetrahydrofuran and other solvents may also be employed. The reactiontemperature is not critical, and for example it can be from 0° to 50° C.Reaction at room temperature is preferred. The reaction is generallycomplete in from 1 to 48 hours, and under the preferred conditions thereaction is typically complete in about 24 hours.

The group R³ in the compound of formula (II) is preferably a methylgroup, a hydroxy-protecting group or an ester-forming carboxylic or acarbonic acid residue which can act as such a protecting group. Wherethe group R³ is hydrogen in the compound of formula (II) and istherefore hydrogen in the intermediate product of formula (III), it ispreferably converted to one of the other groups before proceeding withthe step B, using the procedures described above.

Step B consists in esterification of the 26-hydroxy group of thecompound (III) with a carboxylic acid of formula R² COOH (R² is asdefined above) or a reactive derivative thereof, which may be performedunder conditions known per se.

Examples of reactive derivatives include: acid halides such as the acidchloride, acid bromide or acid iodide; acid anhydrides; mixed acidanhydrides; active esters such as the pentachlorophenyl ester orp-nitrophenylester; and active acid amides.

The step B is preferably carried out in the presence of a solvent, thenature of which is not critical, provided that it has no adverse effectupon the reaction.

Examples of suitable solvents include: hydrocarbons, which may bealiphatic or aromatic and which may be halogenated, such as hexane,petroleum ether, benzene, toluene, xylene, chloroform, methylenechloride or chlorobenzene; ethers such as diethyl ether, tetrahydrofuranor dioxane; and esters such as methyl acetate or ethyl acetate. Thereaction will take place over a wide range of temperature and theprecise temperature chosen is not critical to the invention. Thereaction may be conveniently carried out at a temperature of from 0° C.to 100° C. and more preferably at a temperature of from 20° C. to 50° C.The time required for the reaction may vary, depending upon manyfactors. A period of from 30 minutes to 3 hours will normally suffice.

Generally, from 1 to 10 equivalents, more preferably from 1.5 to 4equivalents of the acid or its reactive derivative, are used per mole ofthe compound of formula (III).

Where the acid itself is employed, the reaction is preferably effectedin the presence of a dehydrating agent, such as dicyclohexylcarbodiimide(DCC), ethyl polyphosphate (PPE), mesitylenesulfonyl triazolide (MST),p-toluenesulfonic acid or sulfuric acid, more preferably DCC. The amountof dehydrating agent is normally from 1 to 5 equivalents, preferably 1.5to 4 equivalents. Where DCC is employed, the reaction may convenientlybe carried out in the presence of a catalytic amount of a base such aspyridine or 4-pyrrolidino-pyridine.

Where a reactive derivative of the acid is employed, the reaction ispreferably effected in the presence of a base, more preferably anorganic base such as triethylamine, N,N-dimethylaniline, pyridine,4-dimethylaminopyridine, 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) or1,8-diazabicyclo[5.4.0]undecene-7 (DBU). The amount of base is normallyfrom 2 to 8 equivalents.

Where the reaction product of Step B bears a silyl protecting group, itcan easily be removed to restore the 5-hydroxy group. The deprotectionmay be achieved by using a dilute acid such as dilute hydrochloric acidor dilute sulfuric acid; an organic acid such as formic acid or aceticacid; p-toluenesulfonic acid/tetrabutylammonium fluoride; or hydrogenfluoride/pyridine; amongst which dilute hydrochloric acid and hydrogenfluoride/pyridine are preferred. The acid is normally in excess, and ispreferably from about 2 to 100 equivalents.

The deprotection reaction is preferably carried out in the presence of asolvent, the nature of which is not critical, provided that it has noadverse effect upon the reaction. Examples of suitable solvents include:hydrocarbons, which may be aliphatic or aromatic and which may behalogenated, such as hexane, petroleum ether, benzene, toluene,chloroform, methylene chloride or dichloroethane; ethers such as diethylether, tetrahydrofuran, dioxane or dimethoxyethane; alcohols such asmethanol or ethanol; nitriles such as acetonitrile or propionitrile; andmixtures of these solvents.

The reaction will take place over a wide range of temperature and theprecise temperature chosen is not critical to the invention. However,the reaction may be conveniently carried out at a temperature of from-20° C. to 70° C. and more preferably at a temperature of from -10° C.to 30° C. The time required for the reaction may vary, depending uponmany factors; however, a period of from 30 minutes to 24 hours,preferably from 30 minutes to 6 hours, will normally suffice.

A compound of formula (I) where R³ is hydrogen may be subjected toesterification with a carboxylic acid or a carbonic acid, or a reactivederivative thereof, to give a compound esterified a the 5-position.

After completion of the steps of the reaction sequence, the resultingproduct can be recovered from the reaction mixture by conventional meansand, if necessary, may be further purified by such conventional means asthe various chromatography techniques, particularly columnchromatography. The compound of formula (I) will sometimes be obtainedas a mixture of such compounds, and they need not necessarily beseparated from each other.

The starting materials of formula (II) are known compounds or may beprepared by methods described in the literature. The reader is referred,for example, to British Patent Specification 1,390,336; Japanese PatentApplication Kokai 57-120589; J Am Chem Soc, 1981, 103, 4216; U.S. Pat.Nos. 4,199,569 and 4,289,760; British Patent Specification 2,166,436;European Patent Specification 215,654; Belgium Patent 904,709; U.S.Reissue Pat. No. 32,034; U.S. Pat. No. 4,457,920: and European Patent2615; which texts are all incorporated herein by reference.

Conventional procedures can be adopted to convert a compound wherein thegroup R³ is a hydrogen atom to a desired compound wherein the group R³takes one of the other meanings. Such conversion is preferably effectedbefore the steps A and B are carried out.

Methylation at the 5-hydroxy position can be achieved using thetechniques described, for example, in European Patent specification237,341.

Protection of the 5-hydroxy group with a protecting group such as asilyl group can be achieved for instance by reaction with a silyl halidein a solvent, advantageously in the presence of a base.

There is no particular limitation on the nature of the solvent forsiliylation, provided that it is inert to the reaction. Preferredsolvents include hydrocarbons, such as hexane or benzene; chlorinatedhydrocarbons such as methylene chloride, or chloroform; ethers such asdiethyl ether; and polar solvents such as tetrahydrofuran, acetonitrile,dimethylformamide, dimethylacetamide, dimethyl sulfoxide or pyridine.

Examples of preferred silylating agents include those of the generalformula Si(R')(R")(R'")Z, in which R', R" and R'" each represents a C₁₋₄alkyl group, a benzyl group or a phenyl group, and z represents halogenor other suitable cationic counter-ion. Specific examples of preferredsilylating agents are trialkylsilyl chloride, triarylsilyl chloride andsilyl trifluoromethanesulfonates.

The silylation is typically effected in the presence of a base, thenature of the base is not crucial, but in general organic bases arepreferred to inorganic ones. Examples of bases which can be employedinclude lithium sulfide, imidazole, pyridine, triethylamine anddimethylaminopyridine, particularly imidazole.

Some silylating reagents, such as hexamethyldisilazane,diethyltrimethylsilyl amine, and others work both as the silylatingagent and provide their own base, at the same time, and may be adoptedfor this invention.

Esterification of the 5-hydroxy group with a carboxylic acid or carbonicacid can be carried out using the techniques described for the step Babove.

Procedures are also available to enable conversion of compounds wherein--X--Y-- has some of the given meanings in to compounds wherein --X--Y--takes some of the other meanings. Such procedures are described, forexample, in the European Patent 74,758.

For the starting materials which are natural products, they may take theform of a single isolated compound or a mixture of two or morecompounds, which may be used without separation. For example, sincemixtures of milbemycins A₃ and A₄ are readily available and may easilybe used, they may be subjected to the reaction sequence withoutseparation.

Some of the compounds of formula (I) of this invention may also beobtained as fermentation products.

Thus, the present invention also provides a process for preparing acompound of formula (I) wherein --X--Y-- represents --CH₂ --CH₂ --; R³and R⁴ each represents a hydrogen atom; and (i) R¹ represents a methylgroup and R² represents a 2-methyl-1-propenyl group, (ii) R¹ representsa methyl group and R² represents a 2-methyl-1-butenyl group, or (iii) R¹represents an ethyl group and R² represents a 2-methyl-1-propenyl group.

Such compounds are referred to herein as milbemycins α₁₁ (thepossibility (i) given above), α₁₃ (the possibility (ii) given above),and α₁₄ (the possibility (iii) given above). They may be obtained bycultivation of a productive micro-organism of the genus Streptomyces.Such a micro-organism is the strain SANK 60286 belonging to the genusStreptomyces which was isolated from soil of Miura City, KanagawaPrefecture, Japan.

The milbemycins α₁₁, α₁₃, and α₁₄ form part of a series of compoundsisolated from the fermentation broth of Streptomyces strain SANK 60286and named milbemycins to α₁₁ to α₁₅, as shown in the table below.

    ______________________________________              R.sup.1                    R.sup.2    ______________________________________    α.sub.11                methyl  2-methyl-1-propenyl    α.sub.12                methyl  isobutyl    α.sub.13                methyl  2-methyl-1-butenyl    α.sub.14                ethyl   2-methyl-1-propenyl    α.sub.15                ethyl   isobutyl    ______________________________________

Characteristics of Streptomyces SANK 60286

The mycological properties of actinomycetes strain SANK 60286 are asfollows.

1. Morphological characteristics

This strain is found microscopically to have branched, pale yellow toyellowish brown basal mycelia from which white to yellowish gray aerialmycelia elongate with spiral terminals. In a grown spore chain, 10 ormore spores are observed in a line, and the spores have warty-rugosesurfaces. The strain forms, in some kinds of media, clear gold slime onthe surface of aerial mycelium, and this slime changes to yellowishspots with the culturing process. Sometimes blackish spots are formeddue to humidity at the later stage of culture.

2. Growth on various media

This strain exhibited the properties shown below after culturing at 28°C. for 14 days on various media. The color names and numbers used hereinwere assigned on the basis of the "Guide to Color Standard", a manualpublished by Nippon Shikisai Kenkyusho.

    ______________________________________    medium      property*   characterisics    ______________________________________    sucrose-nitrate                G           good, grayish white (N-9)    agar        AM          good, white                R           yellowish gray                SP          none    glucose-asparagine                G           very good, yellowish gray    agar                    (2-9-11)                AM          good, grayish white (N-9)                R           pale yellow (3-9-10)                SP          none    glycerol-asparagine                G           good, yellowish brown    agar                    (2-9-11)    (ISP 5)     AM          good, white to yellowish                            gray (2-9-11)                R           pale yellow (8-9-11)                SP          none    inorganic-starch                G           very good, light olive    salt agar               (6-8-11)    (ISP 4)     AM          abundant, white to light                            olive gray (4-8-11)                R           yellowish brown (2-9-11)                SP          none    tyrosine agar                G           good, light olive gray    (ISP 7)                 (2-8-11)                AM          good, white to pale                            yellow (3-9-10)                R           pale yellow (6-8-10)                SP          none    peptone-yeast                G           good, yellowish gray    extract-iron            (2-9-12)    agar        AM          good, white    (ISP 6)     R           yellowish gray (4-9-11)                SP          none    nutrient agar                G           good, yellowish gray    (Difco)                 (1-9-10)                AM          slight formation, gray                            (N-9)                R           pale yellow (3-9-10)                SP          none    yeast-extract-                G           very good, yellowish    malt-extract agar       brown (2-9-11)    (ISP 2)     AM          abundant, grayish                            white (N-9)                R           reddish yellow (12-8-9)                SP          pale yellow (8-9-12)    oatmeal agar                G           very good, pale yellow    (ISP 3)                 (8-9-12)                AM          Abundant, grayish white                            (N-8)                R           yellowish brown (2-9-11)                SP          light olive gray (4-7-11)    water agar  G           poor, grayish white (N-9)                AM          slight formation, light                            brownish gray (2-8-8)                R           grayish white (N-9)                SP          none    potato extract-                G           poor, grayish white (N-9)    carrot extract                AM          good, light brownish    agar                    gray (2-8-8)                R           pale yellowish orange                            (2-9-9)                SP          none    ______________________________________     *: G: growth     AM: aerial mycelium     R: reverse surface     SP: soluble pigment

3. Physiological properties

The physiological properties of strain SANK 60286 are shown below.

    ______________________________________    hydrolysis of starch   positive    liquefaction of gelatin                           positive (weak)    reduction of nitrate   positive    coagulation of milk    positive (weak)    (at 28° C. and 37° C.)    peptonization of milk  positive (weak)    (at 28° C. and 37° C.)    range of growing temperature                           18-37° C.    (medium 1)*    production of melanoid pigment    (medium 2)             negative    (medium 3)             negative    (medium 4)             negative    ______________________________________     *: medium 1: yeast extractmalt extract agar (ISP 2)     medium 2: tryptoneyeast extractbroth (ISP 1)     medium 3: peptoneyeast extractiron agar (ISP 6)     medium 4: tyrosine agar (ISP 7)

After culturing at 28° C. for 14 days on Pridham-Gottlieb agar medium,SANK strain 60286 showed utilization of carbon sources as shown in thetable below.

    ______________________________________    sugar         utilization    ______________________________________    D-glucose     ++    L-arabinose   ++    D-xylose      +    i-inositol    ++    D-mannitol    ++    D-fructose    ++    L-rhamnose    ++    sucrose       ++    raffinose     ++    control       -    ______________________________________     ++well utilized     +utilized     -not utilized

4. Cell components

The cell wall of strain SANK 60286 was examined according to the methodreported by B. Becker et al. (Applied Microbiology, 12, 421 (1964)).Since L,L-diaminopimelic acid and glycine could be detected, the cellwall was shown to be cell wall type I. Sugar components in the wholecells were then examined according to the method reported by M. P.Lechevalier (Journal of Laboratory & Clinical Medicine 71, 934 (1968)).No characteristic pattern was observed.

In summary, the strain was shown to belong to the genus Streptomyces ofthe actinomycetes.

Identification of Streptomyces strain SANK 60286 was performed accordingto the standard of ISP (The International Streptomyces Project);Bergey's Manual of Determinative Bacteriology, Eighth Edition; TheActinomycetes by S. A. Waksman; and other recent references onactinomycetes.

When the properties of strain SANK 60286 were compared with those ofother known species of the genus Streptomyces, the morphological andphysiological ones were nearly identical with those of Streptomyceshygroscopicus subsp aureolacrimosus (J Antibiotics 36, 438 (1983)).

A small difference was observed, however, in culture properties betweenthe two strains. It is well-known that the properties of actinomyceteschange in some degree even for the same strain after successivecultures. Therefore, strains cannot always be differentiatedtaxonomically because of a slight difference in culture properties.

For these reasons, strain SANK 60286 which produces milbemycins and α₁₁,α₁₂, α₁₃, α₁₄ and a₁₅ has been identified as Streptomyces hygroscopicussubsp aureolacrimosus SANK 60286. This strain has been deposited inaccordance with the provision of the Budapest Treaty on Oct. 20, 1986 atthe Fermentation Research Institute, Japan, and given the accessionnumber FERM BP-1190. Samples of the strain will be available under therelevant provisions of the Budapest Treaty.

Actinomycetes including Streptomyces hygroscopicus subsp aureolacrimosusSANK 60286 readily undergo mutation both through natural causes and as aresult of artificial treatments such as UV irradiation, radiationtreatment and chemical treatment. The present invention embraces allproductive mutants of strain SANK 60286. These mutant strains alsoinclude any strains obtained by gene manipulation such as generecombination, transduction and transformation. In other words, thisinvention includes all such strains that can produce one or more ofmilbemycins and α₁₁, α₁₃, and α₁₄, and especially strains that cannot beclearly differentiated from strain SANK 60286 or its mutants.

Milbemycins and can be α₁₁, α₁₃, and α₁₄ can be obtained by culturingstrain SANK 60286 in a suitable medium and by collecting milbemycinsfrom the medium. Conventional substances generally employed for theculture of micro-organisms of the genus Streptomyces can be used as thenutrients. For example, the carbon source can be glucose, sucrose,starch, glycerin, thick malt syrup, molasses or soybean oil. Further byway of example, the nitrogen source can be soybean powder, wheat germ,meat extract, peptone, yeast cells, corn steep liquor, ammonium sulfateor sodium nitrate. If necessary, organic and inorganic additives whichpromote the growth of micro-organisms and activate the production ofmilbemycins α₁₁, α₁₃, and α₁₄ and may be used in a suitable combination,as well as inorganic salts such as calcium carbonate, sodium chloride,potassium chloride and phosphates.

In a similar manner to the conventional methods employed for productionof antibiotics, liquid culture, in particular deep liquid culture ismost suitable for the culturing of the micro-organism. The culture isconducted aerobically. A suitable temperature for the culture is from22° to 30° C., and in most cases the culture is carried out at around28° C. Production of milbemycins α₁₁, α₁₃, α₁₄ and typically reaches amaximum after 5 to 15 days, either by shake culture or tank culture.

The production of milbemycins α₁₁, α₁₃, and α₁₄ can be monitored by thefollowing procedure. One ml of the cultured material is taken in a smalltube, 9 ml of 80% aqueous methanol is added, The tube is shaken andcentrifuged. High performance liquid chromatography (such as a H-2151,ODS reverse phase column, Senshu Co. 6×150 mm, and a pump Model 655,Hitachi) is employed. Five μl of the sample is injected, and developedwith a mixed solvent of acetonitrile and water (80:20) at a flow rate of1.5 ml/min. Milbemycins α₁₁, α₁₃ and α₁₄ are monitored by an UV detector(240 nm) and determined by a data Processing unit (such as a Union TechInst MCPD-350PC).

For collecting milbemycins α₁₁, α₁₃, and α₁₄ from the culture medium, anadsorbent such as active carbon, alumina or silica gel; a syntheticadsorbent such as Diaion HP-20 (Mitsubishi Chem. Ind. Ltd.); anadsorbent such as Avicel (Asahi Chem. Ind. Co., Ltd.) or filter paper;an ion exchange resin; or an ion exchange gel filtering material can beemployed. Most effective is the following procedure:

The cultured material is filtered using a filter aid such as diatomite.The cake obtained is extracted with methanol to dissolve the desiredcompounds in aqueous methanol. Water is added, and the mix extractedwith hexane. The hexane solution is evaporated under reduced pressure togive an oily substance which contains milbemycins α₁₁, α₁₃, and α₁₄. Theoily substance containing milbemycins α₁₁, α₁₃, and α₁₄ is adsorbed on aLobar column Si60 (Merck, size B) and eluted with a mixed solvent ofhexane and ethyl acetate (8:2) to collect fractions each containingmilbemycins α₁₁, α₁₃, or α₁₄. Each fraction containing any one of themilbemycins is evaporated under reduced pressure to give an oilysubstance. The oil is mixed with a small amount of methanol, adsorbedonto a Lobar column RP-8 (Merck, size B), and eluted with a mixedsolvent of acetonitrile and water (80:20). The fractions each containingone of these compounds are collected and, after distilling offacetonitrile under a reduced pressure, extracted with ethyl acetate.Finally, by HPLC (reverse phase column), each of milbemycins α₁₁, α₁₃,and α₁₄ can be obtained as a powder. The milbemycins α₁₂ and α₁₅ canalso be obtained in a similar manner.

The compounds of formula (I) of this invention have excellent acaricidalactivity against adults and eggs of the two spotted spider mite(Tetranychus), citrus red mite (Panonychus), European red mite(Panonychus) and rust mites which are parasitic to fruit trees,vegetables and flowering plants, and against Ixodidae, Dermanysside,Sarcoptidae and other parasites which are parasitic to animals. Thecompounds have, in addition, activity against Oestrus, Lucilia,Hypoderma, Gautrophilus: fleas, and lice, among others which areparasitic to animals and birds; domestic insects such as cockroaches,houseflies and other insects; and various harmful insects in agricultureand horticulture area such as aphids, diamondback moth and larvae ofLepidoptera. The compounds of this invention further have activityagainst Meloidogyne, Bursaphelenchus, Rhizoglyphus and other species insoil.

In addition, the compounds of this invention have excellentparasiticidal activity against endoparasites on animals and humans. Inparticular, the compounds are effective not only against nematodesparasitic to domestic animals, poultry and pets such as pigs, sheep,goats, cattle, horses, dogs, cats and fowls, but also against parasitesbelonging to Filariidae or Setariidae and parasites found in thedigestive tract, blood and other tissues and organs of humans.

When the compounds of this invention are intended to be employed foragricultural and horticultural purposes, they can be formulated aspreparations conventionally used for agricultural chemicals such asdusts, wettable powders, emulsifiable concentrates, aqueous or oilysuspensions and aerosols, by mixing them with carriers or any otherauxiliary agents if necessary. The carriers may be natural or synthetic,and inorganic or organic substances which are incorporated inagricultural formulations in order to assist the active ingredient toreach its target site, and to make it easier to store, transport andhandle the active ingredient.

As for suitable solid carriers, there may be mentioned inorganicsubstances such as clays (for example, kaolinite, montmorillonite andattapulgite), talc, mica, pyrophylite, pumice, vermiculite, gypsum,calcium carbonate, dolomite, diatomaceous earth, magnesium carbonate,apatite, zeolite, silicic anhydride and synthetic calcium silicate;vegetable organic substances such as soybean powder, tobacco powder,walnut powder, wheat flour, wood meal, starch and crystalline cellulose;synthetic or natural high molecular compounds such as cumarone resins,petroleum resins, alkyd resins, polyvinyl chloride, polyalkyleneglycols, ketone resins, ester gums, copal gums and dammar gums; waxessuch as carnauba wax and beeswax; and urea.

As for suitable liquid carriers, there may be mentioned paraffinic ornaphthenic hydrocarbons such as kerosene, mineral oil, spindle oil andwhite oil; aromatic hydrocarbons such as benzene, toluene, xylene,ethylbenzene, cumene and methylnaphthalene; chlorinated hydrocarbonssuch as carbon tetrachloride, chloroform, trichloroethylene,monochlorobenzene and o-chlorotoluene; ethers such as dioxane andtetrahydrofuran; ketones such as acetone, methyl ethyl ketone,diisobutyl ketone, cyclohexanone, acetophenone and isophorone; esterssuch as ethyl acetate, amyl acetate, ethylene glycol acetate, diethyleneglycol acetate, dibutyl maleate and diethyl succinate; alcohols such asmethanol, n-hexanol, ethylene glycol, diethylene glycol, cyclohexanoland benzyl alcohol; ether alcohols such as ethylene glycol ethyl ether,ethylene glycol phenyl ether, diethylene glycol ethyl ether anddiethylene glycol butyl ether; polar solvents such as dimethylformamideand dimethylsulfoxide; and water

As for suitable gaseous carriers, air, nitrogen, carbon dioxide andFreon (trade mark) gas may be mentioned. These gases may be mixed forspraying.

In order to improve such properties of the formulations as dispersion,emulsification, spreading, penetration and adherence, various kinds ofsurface active agents and high molecular compounds may be added ifnecessary, by which wettability, adhesion and absorption of theformulation to animal and plant can be strengthened for increase in theeffectiveness.

As for surface active agents employable for emulsification, dispersion,wettability spreading, binding, disintegration control, stabilization ofthe active ingredients, fluidity improvement and rust prevention, any ofnon-ionic, anionic, cationic and amphoteric types may be used, but amongthese non-ionic and/or anionic surface active agents are usually used.As for suitable non-ionic surface active agents, there may be mentioned,for example, the polymerization adducts of ethylene oxide with higheralcohols such as lauryl alcohol, stearyl alcohol, and olealyl alcohol;the polymerization adducts of ethylene oxide with alkylphenols such asiso-octylphenol and nonylphenol; the pplymerization adducts of ethyleneoxide with alkylnaphthols such as butylnaphthol and octylnaphthol: thepolymerization adducts of ethylene oxide with higher fatty acids such aspalmitic acid, stearic acid and oleic acid; the polymerization adductsof ethylene oxide with mono- or dialkylphosphoric acid such asstearylphosphoric acid and dilaurylphosphoric acid; the polymerizationadducts of ethylen oxide with amines such as dodecylamine and stearicamide; higher fatty acid esters of polyalcohols such as sorbitan and thepolymerization adducts of ethylene oxide therewith; and thepolymerization adducts of ethylene oxide with propylene oxide. As forsuitable anionic surface active agents, there may be mentioned, forexample, alkyl sulfate (ester) salts such as sodium lauryl sulfate andamine salts of oleyl alcohol sulfuric acid ester; alkyl sulfonates suchas sodium salt of sulfosuccinic acid dioctyl ester and sodium2-ethylhexenesulfonate; and aryl sulfonates such as sodiumisopropylnaphthalenesulfonate, sodium methylenebis-naphthalenesulfonate, sodium lignin-sulfonate and sodiumdodecylbenzenesulfonate.

In order to improve the properties of the formulation and to enhance thebiological effect, the compositions of this invention may be used incombination with high molecular compounds or other auxiliary substancessuch as casein, gelatin, albumin, glue, sodium alginate, carboxymethylcellulose, methyl cellulose, hydroxyethyl cellulose and polyvinylalcohol.

The above-mentioned carriers and various auxiliary substances may beused alone or in any desired combination depending on the type offormulation, application target and the like factors.

Dusts may contain, for example, from 1 to 25% by weight of activeingredient in general, and a solid carrier as the remainder.

Wettable powders may contain, for example, from 10 to 90% by weight ofactive ingredient in general, and a solid carrier and dispersing andwetting agent as the remainder. If necessary, a protective colloidagent, thixotropic agent and antiforming agent may be added.

Emulsifiable concentrates may contain, for example, from 5 to 50% byweight of active ingredient in general and from 5 to 20% by weight ofemulsifying agent, and a liquid carrier as the remainder. If necessary,an anticorrosive agent may be added.

Oil formulations may contain, for example, from 0.5 to 5% by weight ofactive ingredient in general and a liquid carrier such as kerosene asthe remainder.

Aerosols may contain, for example, from 0.1 to 5% by weight of activeingredient in general, and optionally a perfume, and an oily and/orliquid carrier as the remainder. Propellants such as liquified petroleumgas, a fluorocarbon gas and carbon dioxide may be charged.

After being formulated variously as mentioned above, the composition ofthis invention may be effectively applied to the crops and domesticanimals parasitized with harmful insects or mites in paddy field,orchard and upland field, by treating the stems and leaves of crops,soil or domestic animals at a concentration from 0.5 to 100 ppm of theactive ingredient.

When the compounds of this invention are intended to be employed foranimals and humans as an anthelmintic agent, the compounds may be orallygiven in the form of drink. The drink is usually a solution, suspensionor dispersion with a suitable non-toxic solvent or water together with asuspending agent such as bentonite and a wetting agent or any othervehicles. In general, the drink contains also an antifoaming agent. Thedrink composition contains generally from about 0.01 to 0.5%, preferablyfrom 0.01 to 0.1%, by weight of the active ingredient.

When the compounds of this invention are intended to be given to animalsin the form of feed, the compounds may be used by dispersing thesehomogeneously into feed, by top-dressing or in the form of pellets. Inorder to obtain the desired anthelmintic effect, the active ingredientsshould be present in general from 0.0001 to 0.02% as the final contentin feed.

The compounds of this invention can be also administered parenterally toanimals by injection into the forestomach, muscle, trachea or bysubcutaneous injection, dissolved or dispersed in a liquid carriervehicle. For the parenteral administration, the active compounds may bepreferably mixed with a suitable vegetable oil such as peanut oil orcotton oil. Such a kind of formulation generally contains from 0.05 to50% by weight of the active ingredient.

The compounds of this invention can also be administered locally bymixing them with a suitable carrier such as dimethylsulfoxide or ahydrocarbon solvent. This kind of formulation can be applied directly tothe surface of the animal body by using a spray or by direct injection.

The most suitable oral dosage for obtaining the best result depends onthe kind of animal to be treated and the type and degree of parasiticinfection. Generally, the dosage is from 0.01 to 100 mg, preferably from0.5 to 50.0 mg, per 1 kg of animal body weight. The dosage may be givensingly or by several divided doses for a relatively short period likefrom 1 to 5 days.

EXAMPLES OF THE INVENTION

The present invention is illustrated in more detail by the followingnon-limiting examples.

EXAMPLE 1 milbemycins α₁₁, α₁₃ and α₁₄ (Compounds No 1, 2 and 3)

In each of ten 500-ml Erlenmeyer flasks, 100 ml of a preculture mediumcontaining sucrose, polypeptone and K₂ HPO₄ (1%, 0.35% or 0.05%),respectively, were inoculated with one loopful of Streptomyceshygrosoopicus subsp aureolacrimosus SANK 60286. After culture on arotary shaker for 48 hours at 28° C., 1 liter of the culture liquid wastransplanted into two 30-liter jar fermenters each containing 20 litersof production medium (sucrose 8%, soybean powder 1%, skimmed milk 1%,yeast extract 0.1%, meat extract 0.1%, CaCO₃ 0.3%, K₂ HPO₄ 0.03%,MgSO₄.7H₂ O 0.1%, FeSO₄.7H2O 0.005%, pH before sterilization 7.2).

The culture was carried out at 28° C. for 12 days in the jar fermentersat a sterilized air flow of 0.5 vvm, under an internal pressure of 0.5kg cm⁻², at a rotation of 40 to 180 rpm and a DO value of 4 to 7 ppm.Thirtytwo liters of the cultured material was mixed with 1.8 kg ofcelite, and filtered. The mycelial cake was washed with 5 liters ofwater and the filtrate and washings were discarded. The mycelial cakewas mixed with 20 l of methanol for 1 hour and after filtration againwashed with 5 liters of methanol.

The filtrate and washings were collected and evaporated under a reducedpressure to give about 2 liters of aqueous residual liquid. This liquidwas extracted three times with 2 liters of hexane. The hexane layer waswashed three times with 1 liter of 2% sodium hydroxide solution. Thehexane layer was dried over anhydrous sodium sulfate and filtered. Thefiltrate was evaporated to give 38 g of an oily substance. Twenty g ofthis oily substance was dissolved in 500 ml of hexane. The solution wasloaded on to a column which had been prepared from 300 g of silica gel(Mallinckrodt Inc. Silica Type 60) with hexane treatment, and developedwith 2 liters of hexane then with hexane/ethyl acetate (3:1).

By monitoring eluted fractions using HPLC milbemycins α₁₁, α₁₂, α₁₃, α₁₄and α₁₅ were collected as a mixture. Evaporation of the solvent gave 1.9g of oily crude product. The whole product was dissolved in 10 ml of 50%methanol/water. The solution was loaded on a column which was preparedfrom 160 g of silanated silica gel (Merck Co., Art 7719) treated with50% methanol/water, and developed with 60% methanol/water, then with 70%methanol/water, and finally with 80% methanol/water. By monitoring theeluted fractions with HPLC, the milbemycins α₁₁, α₁₂, α₁₃, α₁₄ and α₁₅were obtained as a mixture.

Evaporation of the solvent gave 840 mg of an oily crude product. Thewhole product was dissolved in 20 ml of acetonitrile. The acetonitrilesolution was subjected to preparative HPLC using a reverse phase column(Senshu Co., ODS, H-5251, 20×250 mm). 1 ml samples of the solution werecharged each time, and developed with 80% acetonitrile/water at a flowrate of 9.9 ml/min. By monitoring the fractions using UV at 240 nm, thefractions containing product were obtained. From each such fraction, thesolvent was distilled off. Lyophilization of the aqueous residual liquidgave 128 mg of α₁₁, 11.7 mg of α₁₂, 14.8 mg of α₁₃, 43 mg of α₁₄ and 3mg of α₁₅ in the order eluted, and each as a powdery substance.

milbemycin α₁₁

elementary analysis (%): C=68.83, H=8.32

molecular weight: 626 (measured by electron bombardment mass spectrum.The same applies hereafter.)

molecular formula: C₃₆ H₅₀ O₉

specific rotation: [α]²³ +104.3° (C=1.05, CHCl₃) (measured using thesodium-D line. The same applies hereafter.)

UV absorption spectrum: δ_(max) (CH₃ OH) nm (E^(1%), cm ⁻¹) 230 (sh),238 (990), 244 (990), 252 (sh)

IR absorption spectrum: ν_(max) (KBr) cm⁻¹ : 3450, 2950, 1715, 1650,1450, 1380, 1330, 1270, 1220, 1180, 1160, 1140, 1090, 1080, 1050, 1020,990, 940, 850

proton nuclear magnetic resonance spectrum (CDCl₃, 270 MHz): 1.90 (3H,singlet, trans--CH₃ --C(CH₃)═CH--COO--) 2.15 (3H, singlet, cis--CH₃--C(CH₃)═CH--COO--) 3.27 (1H, doublet of quartets, C₂₅ H) 4.00 (1H,doublet, J=6Hz, C₂₅ H) 4.65-4.90 (4H, multiplet, C₂₆ H, C₂₇ H)

electron bombardment mass spectrum: m/Z=626 (M⁺), 558, 526, 508, 400,181, 153 HPLC retention time: 13.4 minutes (ODS, H-2151, 6×150 mm,Senshu Co., developing solvent 80% acetonitrile/water, flow rate 1.5ml/min, monitoring at UV 240 nm. The same conditions apply hereafter.)

milbemycinα₁₂

elementary analysis (%): C=67.04, H=8.01

molecular weight: 628

molecular formula: C₃₆ H₅₂ O₉

specific rotation: [α]²³ +118.3° (C=1.0, CHCl₃)

UV absorption spectrum: δ_(max) (CH₃ OH) nm (E^(1%), cm⁻¹): 238 (750),244(810). 253 (sh)

IR absorption spectrum: ν_(max) (KBr) cm⁻¹ : 3500, 2950, 1740, 1710,1450, 1380, 1330, 1290. 1180. 1120, 1090, 1050, 990

electron bombardment mass spectrum: m/Z=628, 556, 548, 525, 400, 382,329, 181, 153

HPLC retention time: 14.6 minutes

milbemycin α₁₃

elementary analysis (%): C=67.41, H=8.12

molecular weight: 640

molecular formula: C₃₇ H₅₂ O₉

specific rotation: [α]²³ =+91.6° (C=0.89, CHCl₃)

UV absorption spectrum: δ_(max) (CH₃ OH) nm (E^(1%), cm⁻¹): 230 (sh),237 (805), 245 (795), 253 (sh)

IR absorption spectrum: ν_(max) (KBr) cm⁻¹ : 3500, 2950, 1720, 1650,1450, 1380, 1340, 1310, 1270, 1210, 1180, 1140, 1115, 1095, 1050, 990960, 940, 860

proton nuclear magnetic resonance spectrum (CDCl₃, 270 MHz): 1.07 (3H,triplet, CH₃ CH₂ --C(CH₃ ═CH--COO--) 2.16 (3H, singlet, CH₃ --C(C₂H₅)═CH--COO--) 3.27 (1H, doublet of quartets, C₂₅ H) 4.00 (1H, doublet,J=6Hz, C₆ H) 4.65-4.90 (4H, multiplet, C₂₆ H, C₂₇ H)

electron bombardment mass spectrum: M/Z=640 (M⁺), 526, 508, 276, 181,153

HPLC retention time: 16.4 minutes

milbemycin α₁₄

elementary analysis (%): C=67.62, H=7.84

molecular weight: 640

molecular formula: C₃₇ H₅₂ O₉

specific rotation: [α]²³ =+96.1° (C=1.14, CHCl₃)

UV absorption spectrum: δ_(max) (CH₃ OH) nm (E^(1%), cm⁻¹): 230 (sh),237 (800), 244 (810), 253 (sh)

proton nuclear magnetic resonance spectrum (CDCl₃, 270 MHz) : 3.09 (1H,doublet of triplets, J=2.4, 9.3 Hz, C₂₅ H) 4.00 (1H, doublet, J=6.6 Hz,C₆ H) 4.64-4.88 (4H, multiplet, C₂₆ H, C₂₇ H 5.81 (1H, broad singlet C₃H)

IR absorption spectrum: ν_(max) (KBr) cm⁻¹ : 3450, 2950, 1720, 1650,1450, 1380, 1340, 1270, 1220, 1180, 1140, 1100, 1060, 1030, 990, 960,860

electron bombardment mass spectrum: m/Z=640, 540, 522, 276, 263, 195,167

HPLC retention time: 18.0 minutes

milbemycin α₁₅

molecular weight: 642

molecular formula: C₃₇ H₅₄ O₉

electron bombardment mass spectrum: m/Z=642, 555, 540, 414, 396, 385,356, 314, 264, 245, 195, 167

HPLC retention time: 19.6 minutes

EXAMPLE 2 5-O-t-Butyldimethylsilylmilbemycin α₁₄ (Compound No 13)

150 μl of pyridine and 200 μl of 3-methyl-2-butenoyl chloride were addedto a solution of 319.3 mg of26-hydroxy-5-O-t-butyldimethylsilylmilbemycin A₄ in 10 ml of methylenechloride cooled at 0° C. The mixture was then stirred for 30 minutes.The reaction mixture was poured into a saturated aqueous solution ofsodium hydrogencarbonate and extracted with methylene chloride. Theextract was dried over anhydrous magnesium sulfate and concentrated byevaporation.

The residue was purified by column chromatography through silica gel togive 326.2 mg of the title compound (91% yield).

Mass spectrum (EI Method, m/z): 754 (M⁺), 736, 715, 697, 654, 636, 597,589

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm) : 0.11 (3H,singlet, SiCH₃) 0.13 (3H, singlet, SiCH₃) 3.07 (1H, doublet of triplets,J=2.4, 9.3 Hz, C₂₅ H) 3.85 (1H, doublet, J=5.6 Hz, C₆ H) 5.78 (1H,singlet, C₃ H)

EXAMPLE 3 Milbemycin α₁₄ (Compound No 3)

2.5 ml of 68% hydrogen fluoride in pyridine were added to a solution of302.8 mg of 5-O-t-butyldimethylsilylmilbemycin milbemycin α₁₄ in 15 mlof acetonitrile cooled at 0° C., then the mixture was stirred for 2.5hours. At the end of this time, about 300 mg of potassium carbonate andwater were added to the reaction mixture in this order, and then themixture was extracted with chloroform. The extract was dried overanhydrous magnesium sulfate and concentrated by evaporation. The residuewas purified by column chromatography through silica gel to give 232.2mg of the title compound (90% yield) matching the properties of themilbemycin α₁₄ prepared in Example 1.

EXAMPLE 4 26-(2-Butenoyloxy)milbemycin A₄ (Compound No 5)

24 μl of pyridine and 39 μl of 2-butenoyl chloride were added to asolution of 150 mg of 26-hydroxy-5-O-t-butyldimethylsilylmilbemycin A₄in 2 ml of methylene chloride cooled at 0° C., then the mixture wasstirred at room temperature for 3 hours. The reaction mixture was pouredinto ice-water and extracted with ethyl acetate. The extract was driedover anhydrous sodium sulfate and concentrated by evaporation. Theresidue was dissolved in 4 ml of acetonitrile which was then cooled to0° C. 0.5 ml of 68% hydrogen fluoride in pyridine was added to thesolution and the mixture was stirred at room temperature for 1.5 hours.At the end of this time, the reaction mixture was poured into ice-waterand extracted with ethyl acetate. The extract was washed with asaturated aqueous solution of sodium hydrogencarbonate, dried overanhydrous sodium sulfate and concentrated by evaporation. The residuewas purified by preparative thin layer chromatography to give 66.5 mg ofthe title compound (48% yield).

Mass spectrum (EI Method, m/z):

626 (M⁺), 540, 522, 414, 264, 245, 191, 167, 151

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm):

1.99 (3H, doublet of doublets. J=6.9, 1.6 Hz, CH--CH₃ ═CH--COO--) 3.08(1H, doublet of triplets, J=2.4, 9.3 Hz, C₂₅ H 4.84 (1H, doublet, J=13.3Hz, C₂₆ H) 5.87 (1H, quartet doublets, J=1.6, 15.3 Hz, CH-- CH₃ ═CH₃--COO--) 7.03 (1H, quartet of doublets, J=6.9, 15.3 Hz, CH--CH₃═CH--COO--)

EXAMPLE 5 26-(3-Methyl-2-butenoyloxy)milbemycin D (Compound No 16) 0.15ml of 3-methyl-2-butenoyl chloride was added to a solution of 177.3/mgof 26-hydroxy-5-O-t-butyldimethylsilylmilbemycin D and 0.1 ml ofpyridine in 15 ml of methylene chloride cooled at 0° C. The mixture wasthen stirred for 2 hours. The reaction mixture was poured into asaturated aqueous solution of sodium hydrogencarbonate and extractedwith methylene chloride. The extract was dried over anhydrous magnesiumsulfate and concentrated by evaporation. The residue was dissolved in 10ml of acetonitrile which was then cooled to 0° C. 1 ml of 68% hydrogenfluoride in pyridine was added to the solution and the mixture wasstirred for 2 hours. At the end of this time, the reaction mixture waspoured into a saturated aqueous solution of sodium hydrogencarbonate andextracted with ethyl acetate. The extract was dried over anhydrousmagnesium sulfate and concentrated by evaporation. The residue waspurified by column chromatography through silica gel to give 144.7 mg ofthe title compound (86% yield).

Mass spectrum (EI Method, m/z): 654 (M⁺), 618, 554, 428, 410, 356

Nuclear magnetic resonance spectrum (270 MHz, CDCL₃, δ ppm): 3.07 (1H,broad doublet, J=7.7 Hz, C₂₅ H) 4.48 (1H, broad doublet, J=4.0 Hz, C₅ H)4.68 (1H, doublet, J=14.7 Hz, C₂₆ H) 4.79 (1H, doublet, J=14.7 Hz, C₂₆H)

The following compounds were prepared, substantially by following anyone of the appropriate methods described in Examples 2 to 5.

EXAMPLE 6 26-(2-Methyl-2-butenoyloxy)milbemycin A₄ Compound No 6

Mass spectrum (EI Method, m/z): 640 (M⁺), 604, 540, 522, 414

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm):

1.80 (3H, doublet, J=7.2 Hz, CH₃ --CH═C(CH₃)--COO--) 1.85 (3H, singlet,CH₃ --CH═C(CH₃)--COO--) 3.08 (1H, doublet of triplets, J=2.4, 9.3 Hz,C₂₅ H) 4.73 (1H, doublet, J=13.7H, C₂₆ H)

EXAMPLE 7 26-(2-Hexenoyloxy)milbemycin A₄ Compound No 7

Mass spectrum (EI Method, m/z): 654 (M⁺), 618, 522, 504, 414, 396

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 0.93 (3H,triplet, J=7.3 Hz, CH--CH₃ CH₂ CH₂ ═CH--COO--) 4.02 (1H, doublet, J=13.3Hz, C₂₆ H) 4.86 (1H, doublet, J=13.3 Hz, C₂₆ H) 7.01 (1H, triplet ofdoublets, J=6.9, 15.7 H, C₃ H₇ --CH═CH--COO--)

EXAMPLE 8 26-(4-Methyl-2-pentenoyloxy)milbemycin A₄ Compound No 8

Mass spectrum (EI Method, m/z): 654 (M⁺), 618, 522, 414, 396

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 1.07 (6H,doublet, J=6.9 Hz, (CH₃)₂ CH--CH═CH--COO--) 3.08 (1H, doublet oftriplets, J=2.4, 9.3 Hz, C₂₅ H) 4.72 (1H, doublet, J=13.3 Hz, C₂₆ H)4.86 (1H, doublet, J=13.3 Hz, C₂₆ H) 6.99 (1H, doublet of doublets,J=6.5, 15.7 Hz, (CH₃)₂ CH--CH═CH--COO--)

EXAMPLE 9 26-(3-Hexenoyloxy)milbemycin A₄ Compound No 9

Mass spectrum (EI Method, m/z): 654 (M⁺), 414, 279, 195, 167

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.07 (2H,doublet, J=6.4 Hz, CH`--CH₅ ═CH--CH₂ --COO--) 4.68 (1H, doublet, J=12.9Hz, C₂₆ H) 4.79 (1H, doublet, J=12.9 Hz, C₂₆ H)

EXAMPLE 10 26-(4-pentenoyloxy)milbemycin A₄ Compound No 10

Mass spectrum (EI Method, m/z): 640 (M⁺), 604, 522, 264, 195, 167

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.07 (1H,doublet of triplets J=2.4, 9.3 Hz, C₂₅ H) 4.69 (1H, doublet, J=13.7 Hz,C₂₆ H) 4.79 (1H, doublet, J=13.7 Hz, C₂₆ H) 4.99-5.10 (2H, multiplet,CH₂ ═CH--CH₂ CH₂ --COO--)

EXAMPLE 11 216-Cinnamoyloxymilbemycin A₄ Compound No 11

Mass spectrum (EI Method, m/z): 88 (M⁺), 652, 522, 276, 195, 167

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.07 (1H,doublet of triplets, J=2.4, 9.7 Hz, C₂₅ H) 4.81 (1H, doublet, J=13.3 Hz,C₂₆ H) 4.89 (1H, doublet, J=13.3 Hz, C₂₆ H) 6.47 (1H, doublet, J=16.1Hz, Ph--CH═CH--COO--) 7.72 (1H, doublet, J=16.1 Hz, Ph--CH═CH--COO--)

EXAMPLE 12 26-p-Chlorocinnamoyloxymilbemycin A₄ Compound No 12

Mass spectrum (EI Method, m/z):

722 (M⁺), 704, 540, 522, 504

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.07 (1H,doublet of triplets. J=2.4, 8.9 Hz, C₂₅ H 4.81 (1H, doublet, J=13.3 Hz,C₂₆ H) 4.93 (1H, doublet, J=13.3 Hz, C₂₆ H) 6.44 (1H, doublet, J=16.1Hz, p--Cl--Ph--CH═CH--COO--) 7.67 (1H, doublet, J=16.1 Hz,p--Cl--Ph--CH═CH--COO--)

EXAMPLE 13 5-O-propionyl-2-(3-methyl-2-butenoyloxy)milbemycin A₄Compound No 14

Mass spectrum (EI Method, m/z): 696 (M⁺), 604, 504, 414, 396, 356, 264,195, 167, 151

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 1.15 (3H,triplet, J=7.6 Hz, CH₃ CH₂ CO--) 2.40 (2H, quartet, J=7.6 Hz, CH₃ CH₂CO--) 3.07 (1H, broad triplet, J=8.0 Hz, C₂₅ H 4.11 (1H, doublet, J=6.0Hz, C₆ H) 4.50-4.76 (4H, multiplet, C₂₆ H, C₂₇ H) 5.65-5.95 (5H,multiplet, C₃ H, C₅ H, C₉ H, C₁₀ H, (CH₃)₂ C═CH--COO--)

EXAMPLE 14 5-O-Ethoxycarbonyl-2-(3-methyl-2-butenoyloxy)milbemycin A₄Compound No 15

Mass spectrum (EI Method, m/z): 712 (M⁺), 414, 396, 264, 195, 167, 151

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 1.31 (3H,triplet, J=7.1 Hz, CH₃ CH₂ OCOO--) 3.07 (1H, doublet of triplets, J=2.4,8.9 Hz, C₂₅ H) 4.14 (1H, doublet, J=6.1 Hz, C₆ H) 4.19 (2H, quartet,J=7.1 Hz, CH₃ CH₂ OCOO--) 4.57-4.76 (4H, multiplet, C₂₆ H, C₂₇ H) 5.54(1H, doublet of doublets, J=1.6, 6.1 Hz, C₅ H)

EXAMPLE 15 26-(3-Methyl-2-butenoyloxy)ivermectin B_(1a) Compound No 17

Mass spectrum (FAB Method, triethanolamine added, m/z): 1014, 992, 978,962, 934, 878, 830, 299, 194

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.07-3.29(3H, multiplet, C_(4') H, C_(4") H, C₂₅ H) 3.35 (1H, singlet, C₂ H) 3.48(6H, singlet, two --OCH₃) 3.97 (1H, doublet, J=6.1 Hz, C₆ H) 4.49 (1H,broad singlet, C₅ H) 4.69 (2H, broad singlet, C₂₇ H) 4.97 (1H, broaddoublet, J=7.3 Hz, C₁₅ H)

EXAMPLE 16 26-(3-Methyl-2-butenoyloxy) S-541A Compound No 20

Mass spectrum (EI Method, m/z): 710 (M⁺), 592, 523, 468, 448, 423, 376

Nuclear magnetic resonance spectrum (270 MHz, CDCl₃, δ ppm): 3.75 (1H,doublet, J=10.9 Hz, C₂₅ H) 4.67 (1H, doublet, J=13.3 Hz, C₂₆ H) 4.82(1H, doublet, J=13.3 Hz, C₂₆ H) 5.20 (1H, doublet, J=8.9 Hz, C₃₂ H)

EXAMPLE 17 Activity Tests: Adult Mites

Sample solutions were prepared each containing 0.3 ppm, 1 ppm or 3 ppmof individual compounds of this invention, or of one of three controls(milbemycin C, a mixture of milbemycin C and milbemycin C₂ described inJapanese Patent, Laid Open 29742-84; 26-acetoxymilbemycin A₄ ; or26-acetoxyavermectin B₁ a), and 0.01% spreader.

Two-spotted spider mites (Tetranychus urticae) sensitive toorgano-phosphorus insecticides were inoculated on the primary leaf ofcowpea plants (Vigna sinensis Savi). One day after inoculation, 7 ml ofthe sample solution mentioned above was sprayed by a rotary sprayer(Mizuho Seisakusho Co) to give a sprayed amount of 3.5 mg/cm² of leaf.After being sprayed, the leaf was allowed to stand in a room kept at 25°C. After 3 days, whether the adult insects died or not was examined by abinocular microscope and the mortality (%) was calculated. The tablebelow shows the results.

    ______________________________________                      mortality (%)    compound number   3 ppm   1 ppm     0.3 ppm    ______________________________________    1 (α.sub.11)                      100     100         93.0    2 (α.sub.13)                      100       95.6      77.3    3 (α.sub.14)                      100     100       100    5                 100     100       54    6                 100     100       55    7                 100     100       61    8                 100     100       51    9                 100     100       50    10                100     100       44    11                100     100       40    12                100     100       55    14                100     100       65    15                100     100       60    16                100     100       57    17                100     100       53    20                100     100       59    C.sub.1 + C.sub.2 100     100       28    26-acetoxymilbemycin A.sub.4                       92      81       23    26-acetoxyavermectin B.sub.1 a                       83      65       15    ______________________________________

EXAMPLE 18 Activity Tests: Mite Eggs

Sample solutions were prepared each containing 1 ppm or 3 ppm ofindividual compounds of this invention, or of one of three controls(milbemycin C, a mixture of milbemycin C₁ and milbemycin C₂ described inJapanese Patent, Laid Open 29742-84; 26-acetoxymilbemycin A₄ ; or26-acetoxyavermectin B₁ a), and 0.01% spreader.

Female adult two-spotted spider mites were allowed to lay eggs on theprimary leaf of cowpea plants. The adult mites were removed to obtaintest leaves each bearing about 50 eggs.

In a similar manner to that mentioned in the preceding Example, thesample solution was applied to the test leaf. After standing for 2 weeksin a room kept at 25° C., the number of unhatched eggs was counted, andthe unhatched egg rates (%) were calculated.

The table below shows the results.

    ______________________________________                        ovicidal                        activity (%)    compound number     3 ppm   1 ppm    ______________________________________    1 (α.sub.11)  94      51    2 (α.sub.13)  94      71    3 (α.sub.14)  95      57    5                   94      45    6                   62      33    7                   77      50    8                   55      23    10                  53      23    14                  82      41    15                  63      20    16                  67      21    19                  43      20    C.sub.1 + C.sub.2   2.7     2.1    26-Acetoxymilbemycin A.sub.4                        31      12    26-Acetoxyavermectin B.sub.1 a                        4.2     2.4    ______________________________________

It was thus shown that the novel milbemycins of this invention showed ahigh acaricidal effect against adult mites at such a low concentrationas 0.3 ppm, and also possessed useful ovicidal activity.

We claim:
 1. A culture of Streptomyces hygroscopicus subspaureolacrimosus SANK 60286 FERM BP-1190 which, when cultured, producesrecoverable amounts of a compound of formula (I) ##STR6## wherein X isCH₂ ; Y is CH₂ ; R¹ is methyl or ethyl; R² is isobutyl,2-methyl-1-propenyl or 2-methyl-1-butenyl; and R³ and R⁴ are bothhydrogen.
 2. A process for preparing a compound of the following formula(I) ##STR7## wherein X is CH₂ ;Y is CH₂ ; R¹ is methyl or ethyl; R² isisobutyl, 2-methyl-1-propenyl or 2-methyl-1-butenyl; and R³ and R⁴ areboth hydrogen; comprising the steps of fermenting Streptomyceshygroscopicus subsp aureolacrimosus SANK 60286 FERM BP-1190; andthereafter isolating said compound.
 3. The process of claim 2, whereinthe step of isolating said compound comprises isolating the compoundwherein R¹ is methyl and R² is 2-methyl-1-propenyl.
 4. The process ofclaim 2, wherein the step of isolating said compound comprises isolatingthe compound wherein R¹ is methyl and R² is isobutyl.
 5. The process ofclaim 2, wherein the step of isolating said compound comprises isolatingthe compound wherein R¹ is methyl and R² is 2-methyl-1-butenyl.
 6. Theprocess of claim 2, wherein the step of isolating said compoundcomprises isolating the compound wherein R¹ is ethyl and R² is2-methyl-1-propenyl.
 7. The process of claim 2, wherein the step ofisolating said compound comprises isolating the compound wherein R¹ isethyl and R² is isobutyl.